Header encoding for single carrier (SC) and/or orthogonal frequency division multiplexing (OFDM) using shortening, puncturing, and/or repetition

ABSTRACT

Header encoding for SC and/or OFDM signaling using shortening, puncturing, and/or repetition in accordance with encoding header information within a frame to be transmitted via a communication channel employs different respective puncturing patterns as applied to different portions thereof. For example, a first puncturing pattern is applied to a first portion of the frame, and a second puncturing pattern is applied to a second portion of the frame (the second portion may be a repeated version of the first portion). Shortening (e.g., by padding 0-valued bits thereto) may be made to header information bits before they undergo encoding (e.g., in an LDPC encoder). One or both of the information bits and parity/redundancy bits output from the encoder undergo selective puncturing. Moreover, one or both of the information bits and parity/redundancy bits output from the encoder may be repeated/spread before undergoing selective puncturing to generate a header.

CROSS REFERENCE TO RELATED PATENTS/PATENT APPLICATIONS ProvisionalPriority Claims

The present U.S. Utility patent application claims priority pursuant to35 U.S.C. §119(e) to the following U.S. Provisional Patent Applicationswhich are hereby incorporated herein by reference in their entirety andmade part of the present U.S. Utility patent application for allpurposes:

1. U.S. Provisional Application Ser. No. 61/111,685, entitled “60 GHzsingle carrier modulation,”, filed Nov. 5, 2008, pending.

2. U.S. Provisional Application Ser. No. 61/156,857, entitled “Headerencoding/decoding,”, filed Mar. 2, 2009, pending.

3. U.S. Provisional Application Ser. No. 61/235,732, entitled “Headerencoding for single carrier (SC) and/or orthogonal frequency divisionmultiplexing (OFDM) using shortening, puncturing, and/or repetition,”,filed Aug. 21, 2009, pending.

Incorporation by Reference

The following U.S. Utility patent applications are hereby incorporatedherein by reference in their entirety and are made part of the presentU.S. Utility patent application for all purposes:

1. U.S. Utility application Ser. No. 12/605,088, entitled “Baseband unithaving bit repetitive encoded/decoding,”, filed Oct. 23, 2009, pending,which claims priority pursuant to 35 U.S.C. §119(e) to the followingU.S. Provisional Patent Application which is hereby incorporated hereinby reference in its entirety and made part of the present U.S. Utilitypatent application for all purposes:

-   -   a. U.S. Provisional Application Ser. No. 61/111,685, entitled        “60 GHz single carrier modulation,”, filed Nov. 5, 2008,        pending.

2. U.S. Utility application Ser. No. 12/612,640, entitled “Headerencoding/decoding,”, filed concurrently on Nov. 4, 2009, pending, whichclaims priority pursuant to 35 U.S.C. §119(e) to the following U.S.Provisional Patent Applications which are hereby incorporated herein byreference in their entirety and made part of the present U.S. UtilityPatent Application for all purposes:

-   -   a. U.S. Provisional Application Ser. No. 61/111,685, entitled        “60 GHz single carrier modulation,”, filed Nov. 5, 2008,        pending.    -   b. U.S. Provisional Application Ser. No. 61/156,857, entitled        “Header encoding/decoding,”, filed Mar. 2, 2009, pending.    -   c. U.S. Provisional Application Ser. No. 61/235,732, entitled        “Header encoding for single carrier (SC) and/or orthogonal        frequency division multiplexing (OFDM) using shortening,        puncturing, and/or repetition,”, filed Aug. 21, 2009, pending.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The invention relates generally to encoding of a field within a frame tobe transmitted within a communication systems; and, more particularly,it relates to encoding of header information within a communicationdevice that is operative in accordance with one or both of singlecarrier (SC) or orthogonal frequency division multiplexing (OFDM)signaling within such communication systems.

2. Description of Related Art

Data communication systems have been under continual development formany years. One such type of communication system that has been ofsignificant interest lately is a communication system that employsiterative error correction codes (ECCs). Of particular interest is acommunication system that employs LDPC (Low Density Parity Check) code.Communications systems with iterative codes are often able to achievelower bit error rates (BER) than alternative codes for a given signal tonoise ratio (SNR).

A continual and primary directive in this area of development has beento try continually to lower the SNR required to achieve a given BERwithin a communication system. The ideal goal has been to try to reachShannon's limit in a communication channel. Shannon's limit may beviewed as being the data rate to be used in a communication channel,having a particular SNR, that achieves error free transmission throughthe communication channel. In other words, the Shannon limit is thetheoretical bound for channel capacity for a given modulation and coderate.

LDPC code has been shown to provide for excellent decoding performancethat can approach the Shannon limit in some cases. For example, someLDPC decoders have been shown to come within 0.3 dB (decibels) from thetheoretical Shannon limit. While this example was achieved using anirregular LDPC code with a length of one million, it neverthelessdemonstrates the very promising application of LDPC codes withincommunication systems.

The use of LDPC coded signals continues to be explored within many newerapplication areas. Some examples of possible communication systems thatmay employ LDPC coded signals include communication systems employing 4wire twisted pair cables for high speed Ethernet applications (e.g., 10Gbps (Giga-bits per second) Ethernet operation according to the IEEE802.3an (10 GBASE-T) emerging standard) as well as communication systemsoperating within a wireless context (e.g., in the IEEE 802.11 contextspace including the IEEE 802.11n emerging standard).

For any of these particular communication system application areas,near-capacity achieving error correction codes are very desirable. Thelatency constraints, which would be involved by using traditionalconcatenated codes, simply preclude their use in such applications invery high data rate communication system application areas.

Generally speaking, within the context of communication systems thatemploy LDPC codes, there is a first communication device at one end of acommunication channel with encoder capability and second communicationdevice at the other end of the communication channel with decodercapability. In many instances, one or both of these two communicationdevices includes encoder and decoder capability (e.g., within abi-directional communication system). LDPC codes can be applied in avariety of additional applications as well, including those that employsome form of data storage (e.g., hard disk drive (HDD) applications andother memory storage devices) in which data is encoded before writing tothe storage media, and then the data is decoded after beingread/retrieved from the storage media.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to apparatus and methods of operationthat are further described in the following Brief Description of theSeveral Views of the Drawings, the Detailed Description of theInvention, and the claims. Other features and advantages of the presentinvention will become apparent from the following detailed descriptionof the invention made with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 and FIG. 2 illustrate various embodiments of communicationsystems.

FIG. 3 illustrates an embodiment of an LDPC (Low Density Parity Check)code bipartite graph.

FIG. 4A illustrates an embodiment of variable node update with referenceto an LDPC code bipartite graph.

FIG. 4B illustrates an embodiment of check node update with reference toan LDPC code bipartite graph.

FIG. 5 illustrates an embodiment of a frame showing the respectiveportions of preamble, header, and data therein.

FIG. 6 illustrates an embodiment of an apparatus that is operative toprocess header information bits thereby generating a header.

FIG. 7 illustrates an embodiment of an apparatus that is operative toprocess header information bits thereby generating a header inaccordance with an effective coding rate of 1/8 for use in a physicallayer (PHY) frame to be transmitted in accordance with single carrier(SC) signaling.

FIG. 8 illustrates an embodiment of an apparatus that is operative toprocess header information bits thereby generating a header inaccordance with an effective coding rate of 1/12 for use in a PHY frameto be transmitted in accordance with orthogonal frequency divisionmultiplexing (OFDM) signaling.

FIG. 9 illustrates an embodiment of an apparatus that is operative toprocess header information bits thereby generating a header inaccordance with an effective coding rate of K/N (K and N integers) foruse in a PHY frame to be transmitted in accordance with SC signaling.

FIG. 10 illustrates an alternative embodiment of an apparatus that isoperative to process header information bits thereby generating a headerin accordance with an effective coding rate of 1/8 for use in a PHYframe to be transmitted in accordance with SC signaling.

FIG. 11, FIG. 12, and FIG. 13 illustrate various embodiments of anapparatus that is operative to process header information bits therebygenerating a header, by employing selective puncturing, in accordancewith an effective coding rate of 1/7 for use in a PHY frame to betransmitted in accordance with SC signaling.

FIG. 14 illustrates an embodiment of an apparatus that is operative toprocess header information bits thereby generating a header, byemploying selective puncturing, in accordance with an effective codingrate of 9/56 for use in a PHY frame to be transmitted in accordance withSC signaling.

FIG. 15 illustrates an embodiment of performance comparisons of variousLDPC codes, each employing a respective header encoding approach, usingsingle carrier (SC) signaling with quadrature phase shift keying (QPSK)modulation on an additive white Gaussian noise (AWGN) communicationchannel.

FIG. 16 illustrates an embodiment of performance comparisons of variousLDPC codes, each employing a respective header encoding approach, usingSC signaling with an exponential decaying power delay profile (PDP)Rayleigh fading communication channel QPSK modulation.

FIG. 17 illustrates an embodiment of an apparatus that is operative toprocess header information bits thereby generating a header, byemploying selective puncturing, in accordance with an effective codingrate of K/N (K and N integers) for use in a PHY frame to be transmittedin accordance with OFDM signaling.

FIG. 18 illustrates an embodiment of an apparatus that is operative toprocess header information bits thereby generating a header inaccordance with an effective coding rate of 1/12 for use in a PHY frameto be transmitted in accordance with OFDM signaling.

FIG. 19, FIG. 20 and FIG. 21 illustrate various embodiments of anapparatus that is operative to process header information bits therebygenerating a header, by employing selective puncturing, in accordancewith an effective coding rate of 2/21 for use in a PHY frame to betransmitted in accordance with OFDM signaling.

FIG. 22 illustrates an embodiment of an apparatus that is operative toprocess header information bits thereby generating a header, byemploying selective puncturing, in accordance with an effective codingrate of 3/28 for use in a PHY frame to be transmitted in accordance withOFDM signaling.

FIG. 23 illustrates an embodiment of performance comparisons of variousLDPC codes, each employing a respective header encoding approach, usingOFDM signaling with quadrature phase shift keying (QPSK) modulation onan AWGN communication channel.

FIG. 24 illustrates an embodiment of performance comparisons of variousLDPC codes, each employing a respective header encoding approach, usingOFDM signaling with an exponential decaying PDP Rayleigh fadingcommunication channel QPSK modulation.

FIG. 25 illustrates an embodiment of an apparatus that is operative toprocess header information bits thereby generating a header, byemploying selective puncturing including puncturing information bits inaddition to parity/redundancy bits, in accordance with an effectivecoding rate of K/N (K and N integers) for use in a PHY frame to betransmitted in accordance with SC signaling.

FIG. 26 illustrates an embodiment of performance comparisons of variousLDPC codes, each employing a respective header encoding approach, usingSC signaling with QPSK modulation on an AWGN communication channel.

FIG. 27 illustrates an embodiment of performance comparisons of variousLDPC codes, each employing a respective header encoding approach, usingSC signaling with an exponential decaying PDP Rayleigh fadingcommunication channel QPSK modulation.

FIG. 28A illustrates an embodiment of a method for processing headerinformation bits thereby generating a header.

FIG. 28B illustrates an embodiment of an alternatively method forprocessing header information bits thereby generating a header.

DETAILED DESCRIPTION OF THE INVENTION

The goal of digital communications systems is to transmit digital datafrom one location, or subsystem, to another either error free or with anacceptably low error rate. As shown in FIG. 1, data may be transmittedover a variety of communications channels in a wide variety ofcommunication systems: magnetic media, wired, wireless, fiber, copper,and other types of media as well.

FIG. 1 and FIG. 2 are diagrams illustrate various embodiments ofcommunication systems, 100 and 200, respectively.

Referring to FIG. 1, this embodiment of a communication system 100 is acommunication channel 199 that communicatively couples a communicationdevice 110 (including a transmitter 112 having an encoder 114 andincluding a receiver 116 having a decoder 118) situated at one end ofthe communication channel 199 to another communication device 120(including a transmitter 126 having an encoder 128 and including areceiver 122 having a decoder 124) at the other end of the communicationchannel 199. In some embodiments, either of the communication devices110 and 120 may only include a transmitter or a receiver. There areseveral different types of media by which the communication channel 199may be implemented (e.g., a satellite communication channel 130 usingsatellite dishes 132 and 134, a wireless communication channel 140 usingtowers 142 and 144 and/or local antennae 152 and 154, a wiredcommunication channel 150, and/or a fiber-optic communication channel160 using electrical to optical (E/O) interface 162 and optical toelectrical (O/E) interface 164)). In addition, more than one type ofmedia may be implemented and interfaced together thereby forming thecommunication channel 199.

To reduce transmission errors that may undesirably be incurred within acommunication system, error correction, and channel coding schemes areoften employed. Generally, these error correction and channel codingschemes involve the use of an encoder at the transmitter and a decoderat the receiver. Of course, any such communication device implementedwithin such a communication system as described herein, or other type ofcommunication system, may itself be transceiver type communicationdevice that includes an encoder module therein for encoding signals tobe transmitted (e.g., encoding information within signals), and alsoincludes a decoder module therein for decoding signals that are received(e.g., decoding signals to make estimate of information encodedtherein).

Any of the various types and embodiments of encoding and/or decodingdescribed herein can be employed within any such desired communicationsystem (e.g., including those variations described with respect to FIG.1), any information storage device (e.g., hard disk drives (HDDs),network information storage devices and/or servers, etc.) or anyapplication in which information encoding and/or decoding is desired.

Referring to the communication system 200 of FIG. 2, at a transmittingend of a communication channel 299, information bits 201 are provided toa transmitter 297 that is operable to perform encoding of theseinformation bits 201 using an encoder and symbol mapper 220 (which maybe viewed as being distinct functional blocks 222 and 224, respectively)thereby generating a sequence of discrete-valued modulation symbols 203that is provided to a transmit driver 230 that uses a DAC (Digital toAnalog Converter) 232 to generate a continuous-time transmit signal 204and a transmit filter 234 to generate a filtered, continuous-timetransmit signal 205 that substantially comports with the communicationchannel 299. At a receiving end of the communication channel 299,continuous-time receive signal 206 is provided to an AFE (Analog FrontEnd) 260 that includes a receive filter 262 (that generates a filtered,continuous-time receive signal 207) and an ADC (Analog to DigitalConverter) 264 (that generates discrete-time receive signals 208). Ametric generator 270 calculates metrics 209 (e.g., on either a symboland/or bit basis) that are employed by a decoder 280 to make bestestimates of the discrete-valued modulation symbols and information bitsencoded therein 210.

Moreover, one particular type of signal that is processed according tocertain aspects and/or embodiments of the invention includes a framecomposed of various fields including one of which that may becharacterized as a header. Such header information included within aframe to be transmitted within a communication system in accordance withsingle carrier (SC) and/or orthogonal frequency division multiplexing(OFDM) signaling. This encoding of header information may be effectuatedin accordance with shortening, puncturing, and/or repetition.

The decoders of either of the previous embodiments may be implemented toinclude various aspects and/or embodiment of the invention therein. Inaddition, several of the following Figures describe other and particularembodiments (some in more detail) that may be used to support thedevices, systems, functionality and/or methods that may be implementedin accordance with certain aspects and/or embodiments of the invention.One particular type of signal that is processed according to certainaspects and/or embodiments of the invention is an LDPC coded signal. Ageneral description of LDPC codes is provided below as well.

FIG. 3 illustrates an embodiment of an LDPC (Low Density Parity Check)code bipartite graph 300. In the art, an LDPC bipartite graph may alsosometimes be referred to as a “Tanner” graph. An LDPC code may be viewedas being a code having a binary parity check matrix such that nearly allof the elements of the matrix have values of zeroes (e.g., the binaryparity check matrix is sparse). For example, H=(h_(i,j))_(M×N) may beviewed as being a parity check matrix of an LDPC code with block lengthN.

LDPC codes are linear block codes and hence the set of all codewords xεCspans the null space of a parity check matrix, H.Hx ^(T)=0, ∀xεC  (1)

For LDPC codes, H, is a sparse binary matrix of dimension m×n. Each rowof H corresponds to a parity check and a set element h_(ij) indicatesthat data symbol j participates in parity check i. Each column of Hcorresponds to a codeword symbol.

For each codeword x there are n symbols of which m are parity symbols.Hence the code rate r is given by:r=(n−m)/n  (2)

The row and column weights are defined as the number of set elements ina given row or column of H, respectively. The set elements of H arechosen to satisfy the performance requirements of the code. The numberof 1's in the i-th column of the parity check matrix, H, may be denotedas d_(v)(i), and the number of 1's in the j-th row of the parity checkmatrix may be denoted as d_(c)(j). If d_(v)(i)=d_(v) for all i, andd_(c)(j)=d_(c) for all j, then the LDPC code is called a (d_(v), d_(c))regular LDPC code, otherwise the LDPC code is called an irregular LDPCcode.

LDPC codes were introduced by R. Gallager in [1] referenced below (alsoin [2] referenced below) and by M. Luby et al. in [3] also referencedbelow.

[1] R. Gallager, Low-Density Parity-Check Codes, Cambridge, Mass.: MITPress, 1963.

[2] R. G. Gallager, “Low density parity check codes,” IRE Trans. Info.Theory, vol. IT-8, January 1962, pp. 21-28.

[3] M. G. Luby, M. Mitzenmacher, M. A. Shokrollahi, D. A. Spielman, andV. Stemann, “Practical Loss-Resilient Codes,” Proc. 29^(th) Symp. onTheory of Computing, 1997, pp. 150-159.

A regular LDPC code can be represented as a bipartite graph 300 by itsparity check matrix with left side nodes representing variable of thecode bits (or alternatively as the “variable nodes” (or “bit nodes”) 310in a bit decoding approach to decoding LDPC coded signals), and theright side nodes representing check equations (or alternatively as the“check nodes” 320). The bipartite graph 300 (or sometimes referred to asa Tanner graph 300) of the LDPC code defined by H may be defined by Nvariable nodes (e.g., N bit nodes) and M check nodes. Every variablenode of the N variable nodes 310 has exactly d_(v)(i) edges (an exampleedge shown using reference numeral 330) connecting the bit node, v_(i)312, to one or more of the check nodes (within the M check nodes). Theedge 330 is specifically shown as connecting from the bit node, v_(i)312, to the check node, c_(j) 322. This number of d_(v) edges (shown asd_(v) 314) may be referred to as the degree of a variable node i.Analogously, every check node of the M check nodes 320 has exactlyd_(c)(j) edges (shown as d_(c) 324) connecting this node to one or moreof the variable nodes (or bit nodes) 310. This number of edges, d_(c),may be referred to as the degree of the check node j.

An edge 330 between a variable node v_(i) (or bit node b_(i)) 312 andcheck node c_(j) 322 may be defined by e=(i, j). However, on the otherhand, given an edge e=(i, j), the nodes of the edge may alternatively bedenoted as by e=(v(e),c(e)) (or e=(b(e), c(e))). Alternatively, theedges in the graph correspond to the set elements of H where a setelement h_(ji) indicates that an edge connects a bit (e.g., variable)node i with parity check node j.

Given a variable node v_(i) (or bit node b_(i)), one may define the setof edges emitting from the node v_(i) (or bit node b_(i)) byE_(v)(i)={e|v(e)=i} (or by E_(b)(i)={e|b(e)=i}); these edges arereferred to as bit edges, and the messages corresponding to these bitedges are referred to as bit edge messages.

Given a check node c_(j), one may define the set of edges emitting fromthe node c_(j) by E_(c)(j)={e|c(e)=j}; these edges are referred to ascheck edges, and the messages corresponding to these check edges arereferred to as check edge messages. Continuing on, the derivative resultwill be |E_(v)(i)=d_(v) (or E_(b)(i)|=d_(b)) and |E_(c)(j)|=d_(c).

Generally speaking, any codes that can be represented by a bipartitegraph may be characterized as a graph code. It is also noted that anirregular LDPC code may also described using a bipartite graph. However,the degree of each set of nodes within an irregular LDPC code may bechosen according to some distribution. Therefore, for two differentvariable nodes, v_(i) ₁ and v_(i) ₂ , of an irregular LDPC code,|E_(v)(i₁)| may not equal to |E_(v)(i₂)|. This relationship may alsohold true for two check nodes. The concept of irregular LDPC codes wasoriginally introduced within M. Luby et al. in [3] referenced above.

In general, with a graph of an LDPC code, the parameters of an LDPC codecan be defined by a degree of distribution, as described within M. Lubyet al. in [3] referenced above and also within the following reference[4]:

[4] T. J. Richardson and R. L. Urbanke, “The capacity of low-densityparity-check code under message-passing decoding,” IEEE Trans. Inform.Theory, Vol. 47, No. 2, February 2001, pp. 599-618.

This distribution may be described as follows:

Let λ_(i) represent the fraction of edges emanating from variable nodesof degree i and let ρ_(i) represent the fraction of edges emanating fromcheck nodes of degree i. Then, a degree distribution pair (λ, ρ) isdefined as follows:

${{\lambda(x)} = {{\sum\limits_{i = 2}^{M_{v}}{\lambda_{i}x^{i - 1}\mspace{14mu}{and}\mspace{14mu}{\rho(x)}}} = {\sum\limits_{i = 2}^{M_{c}}{\rho_{i}x^{i - 1}}}}},$where M_(v) and M_(c) represent the maximal degrees for variable nodesand check nodes, respectively.

While many of the illustrative embodiments described herein utilizeregular LDPC code examples, it is noted that certain aspects and/orembodiments of the invention are also operable to accommodate bothregular LDPC codes and irregular LDPC codes.

It is also noted that many of the embodiments described herein employthe terminology of “bit node” and “bit edge message”, or equivalentsthereof. Oftentimes, in the art of LDPC decoding, the “bit node” and“bit edge message” are alternatively referred to as “variable node” and“variable edge message”, in that, the bit values (or variable values)are those which are attempted to be estimated. Either terminology can beemployed in accordance with certain aspects of the invention.

FIG. 4A illustrates an embodiment 401 of variable node update withreference to an LDPC code bipartite graph. FIG. 4B illustrates anembodiment 402 of check node update with reference to an LDPC codebipartite graph. These two diagrams may be considered in conjunctionwith one another.

A signal received from a communication channel undergoes appropriatedemodulation (e.g., processing within an analog front end includingdigital sampling, filtering, gain adjustment, etc.) to generate areceived bit sequence. Then, log-likelihood ratios (LLRs) are calculatedfor each bit location within the received bit sequence. These LLRscorrespond respectively to bit nodes of the LDPC code and itscorresponding LDPC bipartite graph.

During initialization, the LLRs are employed for the bit edge messages(e.g., extrinsic information) for each edge emanating from eachrespective variable node. Thereafter, check node processing or checknode updating is performed using the original bit edge messages (e.g.,the calculated LLRs). These updated check edge messages are thenemployed to perform bit node processing or bit node updating to updatethe variable node soft information for use in the next decodingiteration. The variable node soft information is then used to calculatethe variable node edge messages (extrinsic information) for this nextdecoding iteration.

These variable node edge messages are then used in accordance with checknode processing or check node updating to calculate updated check edgemessages. Subsequently, these most recently updated check edge messagesare then employed to perform bit node processing or bit node updating toupdate the variable node soft information once again.

After a final decoding iteration, which may be determined based on someparameter (e.g., a predetermined number of decoding iterations or whenall syndromes of the LDPC code equal zero), the last calculated variablenode soft information may undergo hard limiting (e.g., in a slicer) togenerate estimates of the bits encoded within the received signal.

FIG. 5 illustrates an embodiment 500 of a frame showing the respectiveportions of preamble, header, and data therein. A frame, such as aphysical layer frame, that gets transmitted from a communication deviceinto a communication channel may have the form as described in thisdiagram. While many of the frames described herein are described withreference to a digital format, it is of course noted that a digitalsignal may undergo a variety of processing (e.g., digital to analogconversion, frequency conversion, filtering [analog or digital],scaling, etc.) to generate a continuous time signal that is launchedinto the communication channel.

In this diagram, the frame includes a preamble, a header, and data(alternatively referred to as the payload portion of the frame). Thedata generally includes the actually information to be transmitted froma first location to a second location.

The preamble includes a set of sequences (which may be repetitive) for avariety of applications including: initial frame/burst detection,carrier frequency acquisition, automatic gain control (AGC), timingrecovery, channel estimation, noise/interference estimation, and/orinformation employed for other applications.

In one design, the preamble may be the same for both the single carrier(SC) modulation and orthogonal frequency division multiplexing (OFDM)PHY modes of operation. The preamble may be encoded as a set of Golaysequences (or other sequences with good correlation properties) encodedusing BPSK followed by ±π/2 (e.g., ±90° rotation per symbol.

Header information bits undergo encoding (e.g., using the same type ofcode, or variant of the same base code, as is employed to encode thedata) to form the “header”. The header may be encoded/modulated usingeither SC modulation or OFDM. OFDM uses a certain number of datasub-carriers (e.g., 336) and a certain number of pilots/fixedsub-carriers (e.g., 16). In comparison, SC modulation may use binaryphase shift keying (BPSK) modulation with ±π/2 (e.g., ±90° rotation persymbol. The header information bits (that undergo encoding to form theheader) include all information required to make a frameself-describing. For example, the include information corresponding tomodulation/coding set for the data field (e.g., code rate, code type,constellation/mapping, etc.), the length of the data in octets or timeduration, and/or any additional training information (such as may beemployed in accordance with beamforming in certain wireless contextssuch as multiple input multiple output (MIMO) communication systems).The data field may be modulated using either SC modulation or OFDM usingany of a variety of possible constellations and mappings.

A novel means is presented herein for generating the header that allowsfor providing a flexible header bits size for both SC (single carrier)and orthogonal frequency division multiplexing (OFDM) physical layer(PHY). The final output size of the header may be targeted to be apredetermined size (e.g., generally X bits, or specific values such as448 bits for a SC PHY and 672 bits for an OFDM PHY. The OFDM header andSC header encodings are aligned (e.g., use the rate 3/4 of size 672 LDPCcode as base code for both models).

In the OFDM PHY, the preamble is followed by the PLCP header (e.g.,shown as header in the diagram). The PLCP header consists of severalfields which define the details of the physical layer (PHY) protocoldata unit (PPDU) being transmitted. The encoding and modulation of theheader in accordance with any means or equivalent presented herein. Onceembodiment of the header fields are described in the following Tablerelating to OFDM.

TABLE OFDM - Header Fields Number Start Field Name of bits BitDescription Scrambler 7 0 bits X1-X7 of the initial scrambler state.Initialization MCS 5 7 Index into the Modulation and Coding Scheme tableLength 18 12 Number of data octets in the PSDU. Range 0-262143Additional 1 30 A value of 1 Indicates that this PPDU is PPDUimmediately followed by another PPDU with no IFS or preamble on thesubsequent PPDU. A value of 0 indicates that no additional PPDU followsthis PPDU. Packet Type 2 31 packet type: 0 - regular packet 1 - TRN-Rpacket 2 - TRN-T packet 3 - Reserved Training 5 33 Length of thetraining field Length Aggregation 1 38 Set to 1 to indicate that thePPDU in the data portion of the packet contains an AMPDU; otherwise, setto 0. Reserved 9 39 Set to 0, ignored by receiver. HCS 16 48 Headercheck sequence

In this embodiment described above, all the numeric fields are encodedin unsigned binary, least significant bit first.

Alternatively, in an embodiment including the SC PHY, the preamble isfollowed by the PLCP header (e.g., shown as header in the diagram). ThePLCP header consists of several fields which define the details of thephysical layer (PHY) protocol data unit (PPDU) being transmitted. Theencoding and modulation of the header in accordance with any means orequivalent presented herein. Once embodiment of the header fields aredescribed in the following Table relating to the SCM PHY.

TABLE SCM - Header Fields Number Start Field Name of bits BitDescription Scrambler 7 0 Bits X1-X7 of the initial scrambler stateInitialization MCS 5 7 Index into the Modulation and Coding Scheme tableLength 18 12 Number of data octets in the PSDU. Range 0-262143Additional 1 30 A value of 1 Indicates that this PPDU is PPDUimmediately followed by another PPDU with no IFS or preamble on thesubsequent PPDU. A value of 0 indicates that no additional PPDU followsthis PPDU. Packet Type 2 31 packet type: 0 - regular packet 1 - TRN-Rpacket 2 - TRN-T packet 3 - Reserved Training 4 33 Length of thetraining field Length Reserved 1 37 Set to 0, ignored by receiver.Aggregation 1 38 Set to 1 to indicate that the PPDU in the data portionof the packet contains an AMPDU; otherwise, set to 0. Reserved 9 39 Setto 0, ignored by receiver. HCS 16 48 Header check sequence

Also in this embodiment described above, all the numeric fields areencoded in unsigned binary, least significant bit first.

FIG. 6 illustrates an embodiment of an apparatus 600 that is operativeto process header information bits thereby generating a header. Headerinformation bits (e.g., those bits that includes all appropriateinformation to make the frame self-describing—such as those parameterdescribed above) may be provided to a scrambler circuitry 610. Afterbeing scrambled in the scrambler circuitry 610 (using some scramblingpattern—one pattern/option of which may involve no scramblingwhatsoever), these bits are then provided to a padding circuitry 620that is operative to place at least one pad bit (e.g., a 0-valued bit)therein. The placement of where the at least one pad bit is emplacedwithin the bits provided to the padding circuitry 620 may be varied indifferent embodiments (e.g., at beginning, at end, interspersedthroughout, etc.).

An encoder circuitry 630 operates by encoding padded bit block (outputfrom the padding circuitry 620) thereby generating coded bits. Any of avariety of types of codes (e.g., an LDPC code) may be employed by theencoder circuitry 630. A shorten and/or puncture circuitry 640 mayoperate on the coded bits by shortening coded bits (e.g., removingpadded bits) thereby generating shortened coded bits. The shortenedand/or puncture circuitry 640 may also operate by puncturing at leastone bit from the shortened coded bits thereby generating punctured bits.These punctured bits are passed to a spreader (repeater) 650 that isoperative to perform spreading (e.g., combining, repeating, etc.) thepunctured bits thereby generating a header to be emplaced within a frameto be transmitted from a communication device via a communicationchannel.

FIG. 7 illustrates an embodiment of an apparatus 700 that is operativeto process header information bits thereby generating a header inaccordance with an effective coding rate of 1/8 for use in a physicallayer (PHY) frame to be transmitted in accordance with single carrier(SC) signaling. This diagram shows an encoding scheme for generating anSC header beginning with 56 header information bits such that theencoding is performed in accordance with an effective rate 1/8.

These 56 header information bits undergo scrambling. Thereafter, acertain number of bits are padded thereto, and these bits then undergoencoding with a (224,56) LDPC code that is generated by shortening a(672,504) rate ¾ LDPC code. After the padded bits are removed from thecoded bits output from the LDPC encoder circuitry. A spreading/repeatingof these remaining bits is made using factor of 2. The effective coderate is 56/448=1/8.

FIG. 8 illustrates an embodiment of an apparatus 800 that is operativeto process header information bits thereby generating a header inaccordance with an effective coding rate of 1/12 for use in a PHY frameto be transmitted in accordance with orthogonal frequency divisionmultiplexing (OFDM) signaling. In some respects, the header encoding issimilar to the previous embodiment described with reference to FIG. 7,with at least one difference being that the spreading/repetition isperformed using a factor of 3 (vs. 2 of the previous embodiment). Thisdiagram shows an encoding scheme for generating an OFDM header that isgenerated beginning with 56 information bits and operates in accordancewith an effective rate of 1/12.

In some embodiments, it may be desirable to employ more headerinformation bits (e.g., more than 56 header information bits). Forexample, in some embodiments, to include information to describe all ofthe details corresponding to the date of the frame, a larger number ofheader information bits may be required.

FIG. 9 illustrates an embodiment of an apparatus 900 that is operativeto process header information bits thereby generating a header inaccordance with an effective coding rate of K/N (K and N integers) foruse in a PHY frame to be transmitted in accordance with SC signaling. Incertain of the previous embodiments, only shortening and repetition areemployed. However, selective puncturing is also employed herein, andthat puncturing is applied in a manner that allows for a relatively lowperformance impact of the encoding performed in the generation of theheader.

For example, when more header information bits are employed (e.g., thosebits that include the information that are operative to make a frameself-describing), and when a fixed output size of the eventuallygenerated header is desirable while still employing the same base LDPCcode, then selective puncturing may also be performed in accordance withthe header encoding technique to the header encoding scheme. Thisselective puncturing may employ multiple puncturing patterns as appliedto various portions of a group of bits. For example, the selectivepuncturing may be applied to parity/redundancy bits, tocopies/duplicated portions of those parity/redundancy bits (as may begenerated in accordance with repetition/spreading), to the originalheader information bits themselves, and/or to copies/duplicated portionsof those information bits themselves.

SC PHY Header

Rather than employing a 2 time repetition of a single shortened LDPCcodeword (e.g., as generated by an LDPC encoder), 2 copies of shortenedand punctured LDPC codewords with 2 different puncturing patternsapplied thereto may instead be employed. Of course, generally speaking,N copies of shortened and punctured LDPC codewords with N differentpuncturing patterns applied thereto may instead be employed (N being aninteger).

OFDM PHY Header

Rather than employing a 3 time repetition of a single shortened LDPCcodeword (e.g., as generated by an LDPC encoder), 3 copies of shortenedand punctured LDPC codewords with 3 different puncturing patternsapplied thereto may instead be employed. Of course, generally speaking,N copies of shortened and punctured LDPC codewords with N differentpuncturing patterns applied thereto may instead be employed (N being aninteger).

With respect to any embodiment of the SC PHY header and OFDM PHY headerpresented herein, it is noted that any desired means of combination ofthe bits may be made to generate the final header (e.g., rearranging ofthe bits in accordance with scrambling, interleaving, etc. includingswitching the order of any two or more bits; the order in which theheader information bits, the remaining/non-punctured bits [whether theybe header information bits or parity/redundancy bits] may be emplaced inthe final formed header in accordance with any desired manner or orderas a particular embodiment or implementation would prefer or require.For example, while many of the embodiments presented herein, the headerinformation bits (which are repeated) are followed by theparity/redundancy bits (which are also repeated). However, the order inwhich these bits are included to form the final header may also bechanged without departing from the scope and spirit of the invention(e.g., parity/redundancy bits firstly followed by the header informationbits; alternatively: header information bits followed byparity/redundancy bits then followed by a copy/duplicate of the headerinformation bits then followed by a copy/duplicate of theparity/redundancy bits).

Decoding

In a receiver communication device, a same decoder that is operative toperform decoding of a base LDPC code may also be employed to performheader decoding of each of a SC PHY header and an OFDM PHY header. Inother words, by appropriate design and implementation of the headers (bethey in accordance with SC or OFDM signaling), a single decoder may beprovisioned to decode not only the various types of headers generatedthereby but also the data portions of corresponding frames that havebeen generated in accordance with LDPC encoding as well.

In accordance with decoding, metrics or log-likelihood ratios (LLRs)(e.g., see metric generation operations with reference to FIG. 2) ofrepetition bits are combined (summed) with a proper scaling. Becausedifferent puncturing patterns are applied to different portions of agroup of bits (e.g., that applies a first puncturing pattern to theoriginal portion of the group of bits and a second puncturing pattern toa copied/duplicated portion of the group of bits), then intelligentcombination of the LLRs may be made to recoup any coding loss that mayhave been incurred by the puncturing applied.

In accordance with decoding processing, the LLRs of shortened bits areknown (e.g., because they correspond to bits have predetermined valuessuch as being 0-valued bits). As such, they may be assigned to afixed/predetermined value. Because all of the shortened bits aretypically assigned a common value (e.g., bit value of 0), the LLRscorresponding thereto may all be assigned to the samefixed/predetermined value.

However, because the values of the punctured bits are unknown, the LLRscorresponding thereto are unknown and may all be assigned apredetermined value (e.g., 0). However, by using the differentpuncturing patterns for different repetition blocks, any unknown LLR maybe avoided after combining with LLRs generated by other repetitionblocks.

With these new approaches, comparing to the previous art the newencoding schemes with longer information bits will have better or equalperformance after offsetting the effective code rate gain.

In the embodiment of FIG. 9, certain parameters are given including: theoutput size of SC header encoding=N bits (e.g., N=448), and the rate R(L,T) LDPC code, say LDPC(R), where L is the block size and T is thesize of information bits.

The K header information bits (where K≦T) may undergo scrambling therebygenerating the bits d(1), . . . , d(K) that then undergo padding. Afterpadding T-K 0 bits thereto (e.g., shown as z(K+1), . . . , z(T) 0-valuedbits that are padded after the K information bits (shortening)), thenthese K header information bits and the padded bits are provided to anLDPC encoder circuitry. Of course, it is noted that zero-valued bits(e.g., padded bits) are not transmitted via the communication channel(e.g., on the air in a wireless communication channel embodiment).

The LDPC encoder circuitry is operative to encode d(1), . . . , d(K),z(K+1), . . . , z(T) using an LDPC code, LDPC(R), to get L-Tparity/redundancy bits, shown as p(1), . . . , p(L-T).

Two separate and distinct puncturing patterns are employed, depicted aspunc[1] and punc[2], respectively, on L-T parity bits, respectively, toget two sub-sequences of parity bits, say p(set1)={p(i₁), p(i₂), . . . ,p(i_(a))}, p(set2)={p(j_(i)), p(j₂), . . . , p(j_(b))} such that2×K+a+b=N. It is noted that punc[1] is a subset of {1, . . . , L-T} ofsize L-T-a, and punc[2] is a subset of {1, . . . , L-T} of size L-T-b.The output duplicated information bits, e.g., d(1), . . . , d(K), d(1),. . . , d(K), are followed by p(set1) and p(set2). The effective coderate of such a header encoding approach is K/N.

While this embodiment shows an example of combining the bits (e.g.,using a spreading circuitry) to generate the header by employing theinformation bits, e.g., d(1), . . . , d(K), d(1), . . . , d(K), arefollowed by p(set1) and p(set2), as described above, with respect to anyembodiment of the SC PHY header and OFDM PHY header presented herein. Inan alternative embodiment, the header is generated by employing theinformation bits, e.g., d(1), . . . , d(K) followed by p(set1), followedby a duplicate of the information bits, d(1), . . . , d(K), and thenfollowed by p(set2).

It is again noted that any desired means of combination of the bits maybe made to generate the final header (e.g., rearranging of the bits inaccordance with scrambling, interleaving, etc. including switching theorder of any two or more bits; the order in which the header informationbits, the remaining/non-punctured bits [whether they be headerinformation bits or parity/redundancy bits] may be emplaced in the finalformed header in accordance with any desired manner or order as aparticular embodiment or implementation would prefer or require. Forexample, while many of the embodiments presented herein, the headerinformation bits (which are repeated) are followed by theparity/redundancy bits (which are also repeated). However, the order inwhich these bits are included to form the final header may also bechanged without departing from the scope and spirit of the invention(e.g., parity/redundancy bits firstly followed by the header informationbits; alternatively: header information bits followed byparity/redundancy bits then followed by a copy/duplicate of the headerinformation bits then followed by a copy/duplicate of theparity/redundancy bits).

FIG. 10 illustrates an alternative embodiment of an apparatus 1000 thatis operative to process header information bits thereby generating aheader in accordance with an effective coding rate of 1/8 for use in aPHY frame to be transmitted in accordance with SC signaling. Thisembodiment employs no puncturing therein, and consequently no selectivepuncturing therein that applied different puncturing patterns todifferent portions of the block. This embodiment may be referred to asSC header encoding example 1 as having an effective rate 1/8, K=56,N=448, (672,504) LDPC code. Again, no puncturing is performed in thisembodiment, i.e. punc[1]=punc[2]=Ø.

One embodiment forms the header (e.g., by using a spreader circuitry) byemploying the information bits, e.g., d(1), . . . , d(56), d(1), . . . ,d(56), followed by p(1), . . . , p(168) and p(1), . . . , p(168).However, in an alternative embodiment, the header is generated byemploying the information bits, e.g., d(1), . . . , d(56) followed byp(1), . . . , p(168), then followed by a duplicate of the informationbits, d(1), . . . , d(56), and then followed by p(1), . . . , p(168).Again, any desired means of combination of the bits may be made togenerate the final header.

FIG. 11, FIG. 12, and FIG. 13 illustrate various embodiments of anapparatus 1100, 1200, and 1300, respectively, that is operative toprocess header information bits thereby generating a header, byemploying selective puncturing, in accordance with an effective codingrate of 1/7 for use in a PHY frame to be transmitted in accordance withSC signaling.

Referring to embodiment 1100 of FIG. 11, a greater number of headerinformation bits are employed than in certain previous embodiments(e.g., 64 header information bits vs. 56 header information bits). Inaddition, puncturing of selected bits is performed in this embodiment1100. A common puncturing pattern is applied to different portionsthereof.

This embodiment 1100 may be referred to as SC header encoding example 2as having an effective rate 1/7, K=64, N=448, (672,504) LDPC code. Ascan be seen, a common puncturing pattern, depicted aspunc[1]=punc[2]={161, 162, . . . , 168}, is applied to theparity/redundancy bits and the duplicate copy generated there from.

In other embodiments, certain of the header information bits themselvesmay also undergo puncturing (as also presented below in otherembodiments). Again, in this embodiment 1100 as well as in anyembodiment presented herein, any desired means of combination of thebits may be made to generate the final header.

One embodiment forms the header (e.g., by using a spreader circuitry) byemploying the information bits, e.g., d(1), . . . , d(64), d(1), . . . ,d(64), followed by p(1), . . . , p(160) and p(1), . . . , p(160).However, in an alternative embodiment, the header is generated byemploying the information bits, e.g., d(1), . . . , d(64) followed byp(1), . . . , p(160), then followed by a duplicate of the informationbits, d(1), . . . , d(64), and then followed by p(1), . . . , p(160).Again, any desired means of combination of the bits may be made togenerate the final header.

Referring to embodiment 1200 of FIG. 12, a greater number of headerinformation bits are employed than in certain previous embodiments(e.g., 64 header information bits vs. 56 header information bits). Inaddition, puncturing of selected bits is performed in this embodiment1200. At least two separate and distinct puncturing patterns are appliedto different portions thereof.

This embodiment 1200 may be referred to as SC header encoding example 3as having an effective rate 1/7, K=64, N=448, (672,504) LDPC code. Ascan be seen, two separate and distinct puncturing patterns, depicted aspunc[1]={161, 162, . . . , 168}, and punc[2]={153, 154, . . . , 160},respectively, are applied to the parity/redundancy bits and theduplicate copy generated there from. After puncturing, theremaining/non-punctured bits are composed of p(153:160) and p(161:168),respectively.

This embodiment 1200 shows the puncturing being performed therein to useconsecutive puncturing. For example, a consecutive/contiguous group ofbits are punctured.

In other embodiments, certain of the header information bits themselvesmay also undergo puncturing (as also presented below in otherembodiments). Again, in this embodiment as well as in any embodimentpresented herein, any desired means of combination of the bits may bemade to generate the final header.

One embodiment forms the header (e.g., by using a spreader circuitry) byemploying the information bits, e.g., d(1), . . . , d(64), d(1), . . . ,d(64), followed by p(1), . . . , p(152), followed by p(153), . . . ,p(160), and p(1), . . . , p(152), followed by p(161), . . . , p(168).However, in an alternative embodiment, the header is generated byemploying the information bits, e.g., d(1), . . . , d(64) followed byp(1), . . . , p(152), followed by p(153), . . . , p(160), then followedby a duplicate of the information bits, d(1), . . . , d(64), and thenfollowed by p(1), . . . , p(152), followed by p(161), . . . , p(168).Again, any desired means of combination of the bits may be made togenerate the final header.

Referring to embodiment 1300 of FIG. 13, a greater number of headerinformation bits are employed than in certain previous embodiments(e.g., 64 header information bits vs. 56 header information bits). Inaddition, puncturing of selected bits is performed in this embodiment1200. At least two separate and distinct puncturing patterns are appliedto different portions thereof.

This embodiment may be referred to as SC header encoding example 4 ashaving an effective rate 1/7, K=64, N=448, (672,504) LDPC code. As canbe seen, two separate and distinct puncturing patterns, punc[1]={154,156, . . . , 168}, punc[2]={153, 155, . . . , 167}, respectively, areapplied to the parity/redundancy bits and the duplicate copy generatedthere from.

After puncturing, the remaining/non-punctured bits are composed ofp(153,155,157,159,161,163,165,167) andp(154,156,158,160,162,164,166,168), respectively.

This embodiment 1300 shows the puncturing being performed therein to usenon-consecutive puncturing. For example, anon-consecutive/non-contiguous group of bits are punctured. Differentnon-consecutive/non-contiguous portions of the parity/redundancy bitsand the duplicate copy thereof undergo puncturing.

Again, in other embodiments, certain of the header information bitsthemselves may also undergo puncturing (as also presented below in otherembodiments). Also, in this embodiment as well as in any embodimentpresented herein, any desired means of combination of the bits may bemade to generate the final header.

One embodiment forms the header (e.g., by using a spreader circuitry) byemploying the information bits, e.g., d(1), . . . , d(64), d(1), . . . ,d(64), followed by p(1), . . . , p(152), followed byp(153,155,157,159,161,163,165,167), and p(1), . . . , p(152), followedby p(154,156,158,160,162,164,166,168). However, in an alternativeembodiment, the header is generated by employing the information bits,e.g., d(1), . . . , d(64) followed by p(1), . . . , p(152), followed byp(153,155,157,159,161,163,165,167), then followed by a duplicate of theinformation bits, d(1), . . . , d(64), and then followed by p(1), . . ., p(152), followed by p(154,156,158,160,162,164,166,168). Again, anydesired means of combination of the bits may be made to generate thefinal header.

In accordance with the header encoding presented herein, certainembodiments that perform header encoding (e.g., scrambled and encoded)using a single SCM block may be described as described below. The headerwill be encoded using a single SCM block of N_(CBPB) symbols with N_(GI)guard symbols. The bits are scrambled and encoded as follows:

(1) The input header bits (b₁, b₂, . . . , b_(LH)), where LH=64, arescrambled, starting from the eighth bit. to create d_(1s)=(q₁, q₂, . . ., q_(LH))

(2) The LDPC codeword c=(q₁, q₂, . . . , q_(LH), 0₁, 0₂, . . . ,0_(504-LH), p₁, p₂, . . . , p₁₆₈) is created by concatenating 504-LHzeros to the LH bits of d_(u) and then generating the parity bits p₁,p₂, . . . , p₁₆₈ such that Hc^(T)=0, where H is the parity check matrixfor the rate 3/4 LDPC code.

(3) Remove bits LH+1 through 504 and bits 665 through 672 of thecodeword c to create the sequence cs1=(q₁, q₂, . . . , q_(LH), p₁, p₂, .. . , p₁₆₀).

(4) Remove bits LH+1 through 504 and bits 657 through 664 of thecodeword c and then XORed with the one-time pad sequence (starting fromleft and with the LSB the first to be used in each nibble) to create thesequence cs2=(q₁, q₂, . . . , q_(LH), p₁, p₂, . . . , p₁₅₂, p₁₆₁, p₁₆₂,. . . , p₁₆₈).

(5) cs1 and cs2 are concatenated to form the sequence (cs1, cs2). Theresulting 448 bits are then mapped as π/2-BPSK. The N_(GI) guard symbolsare then pre-pended to the resulting N_(CBPB) symbols.

FIG. 14 illustrates an embodiment of an apparatus 1400 that is operativeto process header information bits thereby generating a header, byemploying selective puncturing, in accordance with an effective codingrate of 9/56 for use in a PHY frame to be transmitted in accordance withSC signaling.

In this embodiment 1400, an even greater number of header informationbits are employed than in certain previous embodiments (e.g., 72 headerinformation bits vs. 64 header information bits or 56 header informationbits). In addition, puncturing of selected bits is performed in thisembodiment 1400. At least two separate and distinct puncturing patternsare applied to different portions thereof.

This embodiment may be referred to as SC header encoding example 5(employing K=72 header information bits) as having an effective rate9/56, K=72, N=448, (672,504) LDPC code. As can be seen, two separate anddistinct puncturing patterns, punc[1]={153:168}, punc[2]={137:152},respectively, are applied to the parity/redundancy bits and theduplicate copy generated there from.

After puncturing the 16 positions in each of the parity/redundancy bitsand the duplicate copy generated there from, the remaining/non-puncturedbits are composed of p(137:152) and p(153:168), respectively.

This embodiment 1400 shows the puncturing being performed therein to useconsecutive puncturing. For example, a consecutive/contiguous group ofbits are punctured.

In other embodiments, certain of the header information bits themselvesmay also undergo puncturing (as also presented below in otherembodiments). Again, in this embodiment as well as in any embodimentpresented herein, any desired means of combination of the bits may bemade to generate the final header.

One embodiment forms the header (e.g., by using a spreader circuitry) byemploying the information bits, e.g., d(1), . . . , d(72), d(1), . . . ,d(72), followed by p(1), . . . , p(136), followed by p(137:152), andp(1), . . . , p(136), followed by p(153:158). However, in an alternativeembodiment, the header is generated by employing the information bits,e.g., d(1), . . . , d(64) followed by p(1), . . . , p(136), followed byp(137:152), then followed by a duplicate of the information bits, d(1),. . . , d(64), and then followed by p(1), . . . , p(136), followed byp(153:158). Again, any desired means of combination of the bits may bemade to generate the final header.

Oftentimes performance diagrams are described in the context of BLER(Block Error Rate) [or BER (Bit Error Rate)] versus E_(b)/N_(o) (ratioof energy per bit E_(b) to the Spectral Noise Density N_(o)) or SNR(Signal to Noise Ratio). This term E_(b)/N_(o) is the measure of SNR fora digital communication system. When looking at such performance curves,the BLER [or BER] may be determined for any given E_(b)/N_(o) (or SNR)thereby providing a relatively concise representation of the performanceof the decoding approach.

FIG. 15 illustrates an embodiment 1500 of performance comparisons ofvarious LDPC codes, each employing a respective header encodingapproach, using single carrier (SC) signaling with quadrature phaseshift keying (QPSK) modulation on an additive white Gaussian noise(AWGN) communication channel.

The various examples 1, 2, 3, and 4 presented in certain of the previousdiagrams are shown in this diagram to show the relative performancethereof based on a AWGN communication channel.

To compensate for the coding offset incurred by the different effectivecoding rate of 1/8 (corresponding to example 1) when compared to theeffective coding rate of 1/7 (corresponding to examples 2, 3, and 4),the performance curve of example 1 is shifted appropriately to allow foran accurate comparison.

FIG. 16 illustrates an embodiment 1600 of performance comparisons ofvarious LDPC codes, each employing a respective header encodingapproach, using SC signaling with an exponential decaying power delayprofile (PDP) Rayleigh fading communication channel QPSK modulation.

The various examples 1, 2, 3, and 4 presented in certain of the previousdiagrams are shown in this diagram to show the relative performancethereof based on an exponential decaying PDP Rayleigh fadingcommunication channel QPSK modulation.

Again, as with the previous embodiment 1500, to compensate for thecoding offset incurred by the different effective coding rate of 1/8(corresponding to example 1) when compared to the effective coding rateof 1/7 (corresponding to examples 2, 3, and 4), the performance curve ofexample 1 is shifted appropriately to allow for an accurate comparison.

Performance Analysis for SC Header

A net coding gain or loss may be incurred when considering the rate lossof 1/8 comparing to 1/7. However, the net coding gain or loss of theeffective rate 1/8 codes is of course offset by approximately 10 log10((1/7)/(1/8))=0.58 dB (e.g., see doted curves in the performancediagrams as referenced above).

In comparing to the effective rate 1/8 code (e.g., example 1) and theeffective rate 1/7 codes (e.g., examples 2, 3, and 4) on an AWGNchannel, the following observations may be made. Example 3 and 4 have nonet performance loss. Example 2 has net 0.25 dB performance loss. Anabsolute (not counting rate gain) SNR loss of Example 3 and 4 is 0.58dB.

In comparing to the effective rate 1/8 code (e.g., example 1) and theeffective rate 1/7 codes (e.g., examples 2, 3, and 4) on OFDM withexponentially-decaying PDP Rayleigh channel, the following observationsmay be made. Examples 2, 3 and 4 all have no net performance loss. Anabsolute (not counting rate gain) SNR loss of Examples 2, 3 and 4 is0.58 dB.

OFDM Header Encoding Scheme

FIG. 17 illustrates an embodiment 1700 of an apparatus that is operativeto process header information bits thereby generating a header, byemploying selective puncturing, in accordance with an effective codingrate of K/N (K and N integers) for use in a PHY frame to be transmittedin accordance with OFDM signaling.

Again, when more header information bits are employed (e.g., those bitsthat include the information that are operative to make a frameself-describing), and when a fixed output size of the eventuallygenerated header is desirable while still employing the same base LDPCcode, then selective puncturing may also be performed in accordance withthe header encoding technique to the header encoding scheme. Thisselective puncturing may employ multiple puncturing patterns as appliedto various portions of a group of bits. For example, the selectivepuncturing may be applied to parity/redundancy bits, tocopies/duplicated portions of those parity/redundancy bits (as may begenerated in accordance with repetition/spreading), to the originalheader information bits themselves, and/or to copies/duplicated portionsof those information bits themselves.

In accordance with OFDM signaling, certain operational parameters may bedefined including: output size of OFDM header encoding, say N; rate R(L,T) LDPC code, say LDPC(R), where L is the block size and T is thesize of information bits.

The K header information bits (where K≦T) may undergo scrambling therebygenerating d(1), . . . , d(K) that then undergo padding.

The K header information bits (where K≦T) may undergo scrambling therebygenerating the bits d(1), . . . , d(K) that then undergo padding. Afterpadding T-K 0 bits thereto (e.g., shown as z(K+1), . . . , z(T) 0-valuedbits that are padded after the K information bits (shortening)), thenthese K header information bits and the padded bits are provided to anLDPC encoder circuitry. Of course, it is noted that zero-valued bits(e.g., padded bits) are not transmitted via the communication channel(e.g., on the air in a wireless communication channel embodiment).

The LDPC encoder circuitry is operative to encode d(1), . . . , d(K),z(K+1), . . . , z(T) using an LDPC code, LDPC(R), to get L-Tparity/redundancy bits, shown as p(1), . . . , p(L-T).

With respect to OFDM, more than two separate and distinct puncturingpatterns are employed. Instead three separate and distinct puncturingpatterns are employed, depicted as punc[1], punc[2], and punc[3],respectively, on L-T parity bits, respectively, to get two threesub-sequences of un-punctured parity bits, say p(set1)={p(i₁), p(i₂), .. . , p(i_(a))}, p(set2)={p(j₁), p(j₂), . . . , p(j_(b))}, andp(set2)=p(k₁), p(k₂), . . . , p(k_(c)) such that 3×K+a+b+c=N.

It is noted that punc[1] is a subset of {1, . . . , L-T} of size L-T-a,punc[2] is a subset of {1, . . . , L-T} of size L-T-b and punc[3] is asubset of {1, . . . , L-T} of size L-T-c. The output duplicatedinformation bits, e.g., d(1), . . . , d(K), d(1), . . . , d(K), arefollowed by p(set1), p(set2) and p(set3). The effective code rate ofsuch a header encoding approach is K/N.

While this embodiment shows an example of combining the bits to generatethe header by employing the information bits, e.g., d(1), . . . , d(K),d(1), . . . , d(K), are followed by p(set1) and p(set2), as describedabove, with respect to any embodiment of the SC PHY header and OFDM PHYheader presented herein.

While this embodiment shows an example of combining the bits (e.g.,using a spreading circuitry) to generate the header by employing theinformation bits, e.g., d(1), . . . , d(K), d(1), . . . , d(K), d(1), .. . , d(K), are followed by p(set1), p(set2), and p(set3), as describedabove, with respect to any embodiment of the SC PHY header and OFDM PHYheader presented herein. In an alternative embodiment, the header isgenerated by employing the information bits, e.g., d(1), . . . , d(K)followed by p(set1), followed by a duplicate of the information bits,d(1), . . . , d(K), and then followed by p(set2), followed by aduplicate of the information bits, d(1), . . . , d(K), and then followedby p(set3).

It is again noted that any desired means of combination of the bits maybe made to generate the final header (e.g., rearranging of the bits inaccordance with scrambling, interleaving, etc. including switching theorder of any two or more bits; the order in which the header informationbits, the remaining/non-punctured bits [whether they be headerinformation bits or parity/redundancy bits] may be emplaced in the finalformed header in accordance with any desired manner or order as aparticular embodiment or implementation would prefer or require. Forexample, while many of the embodiments presented herein, the headerinformation bits (which are repeated) are followed by theparity/redundancy bits (which are also repeated). However, the order inwhich these bits are included to form the final header may also bechanged without departing from the scope and spirit of the invention(e.g., parity/redundancy bits firstly followed by the header informationbits; alternatively: header information bits followed byparity/redundancy bits then followed by a copy/duplicate of the headerinformation bits then followed by a copy/duplicate of theparity/redundancy bits).

FIG. 18 illustrates an embodiment of an apparatus 1800 that is operativeto process header information bits thereby generating a header inaccordance with an effective coding rate of 1/12 for use in a PHY frameto be transmitted in accordance with OFDM signaling.

This embodiment employs no puncturing therein, and consequently noselective puncturing therein that applied different puncturing patternsto different portions of the block. This embodiment may be referred toas OFDM header encoding example 1 as having an effective rate 1/12,K=56, N=672, (672,504) LDPC code. Again, no puncturing is performed Ithis embodiment, i.e. punc[1]=punc[2]=punc[3]=Ø.

One embodiment forms the header (e.g., by using a spreader circuitry) byemploying the information bits, e.g., d(1), . . . , d(56), d(1), . . . ,d(56), d(1), . . . , d(56), followed by p(1), . . . , p(168), p(1), . .. , p(168), and p(1), . . . , p(168). However, in an alternativeembodiment, the header is generated by employing the information bits,e.g., d(1), . . . , d(56) followed by p(1), . . . , p(168), thenfollowed by a duplicate of the information bits, d(1), . . . , d(56),and then followed by p(1), . . . , p(168), and then followed by aduplicate of the information bits, d(1), . . . , d(56), and thenfollowed by p(1), . . . , p(168). Again, any desired means ofcombination of the bits may be made to generate the final header.

FIG. 19, FIG. 20 and FIG. 21 illustrate various embodiments of anapparatus 1900, 2000, and 2100, respectively, that is operative toprocess header information bits thereby generating a header, byemploying selective puncturing, in accordance with an effective codingrate of 2/21 for use in a PHY frame to be transmitted in accordance withOFDM signaling.

Referring to embodiment 1900 of FIG. 19, a greater number of headerinformation bits are employed than in certain previous embodiments(e.g., 64 header information bits vs. 56 header information bits). Inaddition, puncturing of selected bits is performed in this embodiment1900. A common puncturing pattern is applied to different portionsthereof.

This embodiment may be referred to as OFDM header encoding example 2 ashaving an effective rate 2/21, K=64, N=672, (672,504) LDPC code. As canbe seen, a common puncturing pattern, depicted aspunc[1]=punc[2]=punc[3]={161, 162, . . . , 168}, is applied to theparity/redundancy bits and the duplicate two separate copies generatedthere from.

In other embodiments, certain of the header information bits themselvesmay also undergo puncturing (as also presented below in otherembodiments). Again, in this embodiment 1900 as well as in anyembodiment presented herein, any desired means of combination of thebits may be made to generate the final header.

One embodiment forms the header (e.g., by using a spreader circuitry) byemploying the information bits, e.g., d(1), . . . , d(64), d(1), . . . ,d(64), and d(1), . . . , d(64), followed by p(1), . . . , p(160), p(1),. . . , p(160), and p(1), . . . , p(160). However, in an alternativeembodiment, the header is generated by employing the information bits,e.g., d(1), . . . , d(64) followed by p(1), . . . , p(160), thenfollowed by a duplicate of the information bits, d(1), . . . , d(64),and then followed by p(1), . . . , p(160), and then followed by aduplicate of the information bits, d(1), . . . , d(64), and thenfollowed by p(1), . . . , p(160). Again, any desired means ofcombination of the bits may be made to generate the final header.

Referring to embodiment 2000 of FIG. 20, a greater number of headerinformation bits are employed than in certain previous embodiments(e.g., 64 header information bits vs. 56 header information bits). Inaddition, puncturing of selected bits is performed in this embodiment2000. At least two separate and distinct puncturing patterns are appliedto different portions thereof.

This embodiment 1200 may be referred to as OFDM header encoding example3 as having an effective rate 2/21, K=64, N=672, (672,504) LDPC code. Ascan be seen, three separate and distinct puncturing patterns, depictedas punc[1]={161, 162, . . . , 168}, punc[2]={153, 154, . . . , 160}, andpunc[3]={145, 146, . . . , 152}, respectively, are applied to theparity/redundancy bits and the duplicate copies generated there from.After puncturing, the remaining/non-punctured bits are composed ofp(145:160), p(145:152) U p(161:168), p(153:168), respectively.

This embodiment 2000 shows the puncturing being performed therein to useconsecutive puncturing. For example, a consecutive/contiguous group ofbits are punctured. Different consecutive/contiguous portions of theparity/redundancy bits and the duplicate copies thereof undergopuncturing.

Again, in other embodiments, certain of the header information bitsthemselves may also undergo puncturing (as also presented below in otherembodiments). Also, in this embodiment as well as in any embodimentpresented herein, any desired means of combination of the bits may bemade to generate the final header.

One embodiment forms the header (e.g., by using a spreader circuitry) byemploying the information bits, e.g., d(1), . . . , d(64), d(1), . . . ,d(64), and d(1), . . . , d(64), followed by p(1), . . . , p(144),followed by p(145:160), then followed by p(1), . . . , p(144), which isfollowed by p(145:152) U p(161:168), and then followed by p(1), . . . ,p(144) which is followed by p(153:168). However, in an alternativeembodiment, the header is generated by employing the information bits,e.g., d(1), . . . , d(64) followed by p(1), . . . , p(144), followed byp(145:160), then followed by a duplicate of the information bits, d(1),. . . , d(64), and then followed by p(1), . . . , p(144), which isfollowed by p(145:152) U p(161:168), and then followed by a duplicate ofthe information bits, p(1), . . . , p(144) which is followed byp(153:168). Again, any desired means of combination of the bits may bemade to generate the final header.

Referring to embodiment 2100 of FIG. 21, a greater number of headerinformation bits are employed than in certain previous embodiments(e.g., 64 header information bits vs. 56 header information bits). Inaddition, puncturing of selected bits is performed in this embodiment2100. At least three separate and distinct puncturing patterns areapplied to different portions thereof.

This embodiment may be referred to as OFDM header encoding example 4 ashaving an effective rate 2/21, K=64, N=672, (672,504) LDPC code. As canbe seen, three separate and distinct puncturing patterns, depicted aspunc[1]=(1:8), punc[2]=(85:92), and punc[3]=(161:168), respectively, areapplied to the parity/redundancy bits and the duplicate copies generatedthere from. After puncturing, the remaining/non-punctured bits arecomposed of p(set1)=p(9:168), p(set2)=p(1:84) U p(93:168), andp(set3)=p(1:160), respectively.

This embodiment 2100 shows the puncturing being performed therein to useconsecutive puncturing. For example, a consecutive/contiguous group ofbits are punctured. Different consecutive/contiguous portions of theparity/redundancy bits and the duplicate copies thereof undergopuncturing.

Again, in other embodiments, certain of the header information bitsthemselves may also undergo puncturing (as also presented below in otherembodiments). Also, in this embodiment as well as in any embodimentpresented herein, any desired means of combination of the bits may bemade to generate the final header.

While this embodiment shows an example of combining the bits (e.g.,using a spreading circuitry) to generate the header by employing theinformation bits, e.g., d(1), . . . , d(64), d(1), . . . , d(64), d(1),. . . , d(64), are followed by p(set1), p(set2), and p(set3), asdescribed above, with respect to any embodiment of the SC PHY header andOFDM PHY header presented herein. In an alternative embodiment, theheader is generated by employing the information bits, e.g., d(1), . . ., d(64) followed by p(set1), followed by a duplicate of the informationbits, d(1), . . . , d(64), and then followed by p(set2), followed by aduplicate of the information bits, d(1), . . . , d(64), and thenfollowed by p(set3).

In accordance with the header encoding presented herein, certainembodiments that perform header encoding (e.g., scrambled and encoded)using a single OFDM symbol may be described as follows:

(1) The 64 header bits (b₁, b₂, . . . , b_(LH)), where LH=64, arescrambled, starting from the eighth bit, to create q=(q₁, q₂, . . . ,q_(LH))

(2) The sequence q is padded with 440 zeros to obtain a total of 504bits, (q₁, q₂, . . . , q_(LH), 0_(LH+1), 0_(LH+2), . . . , 0₅₀₄), whichare then encoded using the rate-3/4 LDPC code. 168 parity bits, p₁, p₂,. . . , p₁₆₈, are generated.

(3) A sequence c₁ is generated as (q₁, q₂, . . . , q_(LH), p₉, p₁₀, . .. p₁₆₈).

(4) A sequence c₂ is generated as (q₁, q₂, . . . , q_(LH), p₁, p₂, p₈₄,p₉₃, p₉₄, . . . p₁₆₈) XORed with the one-time pad sequence (startingfrom left and with the LSB the first to be used in each nibble).

(5) A sequence c₃ is generated as (q₁, q₂, . . . , q_(LH), p₁, p₂, . . .p₁₆₀) XORed with the one-time pad sequence [which may be different thanthe one above] (starting from left and with the LSB the first to be usedin each nibble).

(6) The sequences c₁, c₂ and c₃ are concatenated to form the 672-bitsequence d=(d₁, d₂, d₃, . . . , d₆₇₂)=(c₁, c₂, c₃).

(7) The 672-bit sequence, d, is then mapped as QPSK in accordance with aparticular mapping of the constellation points therein, pilots (e.g.,pilot symbols) are inserted and the resulting sequence is modulated asan OFDM symbol.

FIG. 22 illustrates an embodiment of an apparatus 2200 that is operativeto process header information bits thereby generating a header, byemploying selective puncturing, in accordance with an effective codingrate of 3/28 for use in a PHY frame to be transmitted in accordance withOFDM signaling.

Referring to embodiment 2200 of FIG. 22, an even greater number ofheader information bits are employed than in certain previousembodiments (e.g., 72 header information bits vs. 64 header informationbits or 56 header information bits). In addition, puncturing of selectedbits is performed in this embodiment 2200. At least three separate anddistinct puncturing patterns are applied to different portions thereof.

This embodiment may be referred to as OFDM header encoding example 5operating on an even greater number of header information bits (e.g.,K=72) and as having an effective rate 3/28, K=72, N=672, (672,504) LDPCcode. As can be seen, three separate and distinct puncturing patterns,each puncturing 16 positions, respectively, are applied to theparity/redundancy bits and the duplicate copies generated there from.After puncturing, the remaining/non-punctured bits are composed ofp(121:152), p(121:136) U p(153:168), and p(137:168), respectively.

This embodiment 2200 shows the puncturing being performed therein to useconsecutive puncturing. For example, a consecutive/contiguous group ofbits are punctured. Different consecutive/contiguous portions of theparity/redundancy bits and the duplicate copies thereof undergopuncturing.

Again, in other embodiments, certain of the header information bitsthemselves may also undergo puncturing (as also presented below in otherembodiments). Also, in this embodiment as well as in any embodimentpresented herein, any desired means of combination of the bits may bemade to generate the final header.

While this embodiment shows an example of combining the bits (e.g.,using a spreading circuitry) to generate the header by employing theinformation bits, e.g., d(1), . . . , d(72), d(1), . . . , d(72), d(1),. . . , d(72), are followed by p(set1), p(set2), and p(set3), asdescribed above, with respect to any embodiment of the SC PHY header andOFDM PHY header presented herein. In an alternative embodiment, theheader is generated by employing the information bits, e.g., d(1), . . ., d(72) followed by p(set1), followed by a duplicate of the informationbits, d(1), . . . , d(72), and then followed by p(set2), followed by aduplicate of the information bits, d(1), . . . , d(72), and thenfollowed by p(set3).

FIG. 23 illustrates an embodiment 2300 of performance comparisons ofvarious LDPC codes, each employing a respective header encodingapproach, using OFDM signaling with quadrature phase shift keying (QPSK)modulation on an AWGN communication channel.

The various examples 1, 2, 3, and 4 presented in certain of the previousdiagrams are shown in this diagram to show the relative performancethereof based on a AWGN communication channel.

To compensate for the coding offset incurred by the different effectivecoding rate of 1/12 (corresponding to example 1) when compared to theeffective coding rate of 2/21 (corresponding to examples 2, 3, and 4),the performance curve of example 1 is shifted appropriately to allow foran accurate comparison.

FIG. 24 illustrates an embodiment 2400 of performance comparisons ofvarious LDPC codes, each employing a respective header encodingapproach, using OFDM signaling with an exponential decaying PDP Rayleighfading communication channel QPSK modulation.

Performance Analysis for OFDM Header

A net coding gain or loss may be incurred when considering rate loss of1/12 comparing to 2/21. However, the net coding gain or loss of theeffective rate 1/12 codes is of course should offset by approximately 10log 10((2/21)/(1/12))=0.58 dB (e.g., see doted curves in the performancediagrams as referenced above).

In comparing to the effective rate 1/12 code (e.g., example 1) and theeffective rate 2/21 codes (e.g., examples 2, 3, and 4) on an AWGNchannel, the following observations may be made. Example 3 has no netperformance loss. Example 4 has net 0.25 dB performance gain. Anabsolute (not counting rate gain) SNR loss of Example 4 is 0.25 dB.

In comparing to the effective rate 1/12 code (e.g., example 1) and theeffective rate 2/21 codes (e.g., examples 2, 3, and 4) on OFDM withexponentially-decaying PDP Rayleigh channel, the following observationsmay be made. Example 3 has 0.12 dB net performance gain. Example 4 hasnet 0.25 dB performance gain. An absolute (not counting rate gain) SNRloss of Example 4 is 0.25 dB.

FIG. 25 illustrates an embodiment of 2500 an apparatus that is operativeto process header information bits thereby generating a header, byemploying selective puncturing including puncturing information bits inaddition to parity/redundancy bits, in accordance with an effectivecoding rate of K/N (K and N integers) for use in a PHY frame to betransmitted in accordance with SC signaling.

A General Header Encoding (Including Selective Puncturing of InformationBits)

These embodiments show how not only may parity/redundancy bits beselectively punctured, but the header information bits themselves (e.g.,those bits that include the information that makes the frameself-describing) may be selectively punctured. As shown in otherembodiments herein where two or more puncturing patterns may be appliedto the parity/redundancy bits and any duplicate copies generate therefrom, similarly two or more puncturing patterns may be applied to theheader information bits and any duplicate copies generate there from.

In accordance with SC signaling, certain operational parameters may bedefined including: output size of the header encoding, say N; rate R(L,T) LDPC code, say LDPC(R), where L is the block size and T is thesize of information bits.

The K header information bits (where K≦T) may undergo scrambling therebygenerating to get c(1), . . . , c(K) that then undergo padding. Afterpadding T-K 0 bits thereto (e.g., shown as z(1), . . . , z(T-K) 0-valuedbits that are padded after the K information bits (shortening)), thenthese K header information bits and the padded bits are provided to anLDPC encoder circuitry. Of course, it is noted that zero-valued bits(e.g., padded bits) are not transmitted via the communication channel(e.g., on the air in a wireless communication channel embodiment).

The LDPC encoder circuitry is operative to encode c(1), . . . , c(K),z(1), . . . , z(T-K) using an LDPC code, LDPC(R), to get the output bitsthat includes parity/redundancy bits, shown as c(1), c(2), . . . , c(K),c(K+1), . . . , c(K+L-T).

Thereafter, M separate and distinct puncturing patterns, depicted aspunc[1], punc[2], . . . , punc[M], respectively, are applied on theK+L-T c bits, respectively, to get the following sub-sequences:c(set1)=c(i_(i)), c(i₂), . . . , c(i_(a1)); c(set2)=c(j₁), c(j₂), . . ., c(j_(a2)); . . . ; c(setM)=c(k₁), c(k₂), . . . , c(k_(aM)),respectively, such that a1+a2+ . . . +aM=N.

The output sets of bits, c(set1), c(set2), . . . , c(setM), are outputin any preferred order. The effective code rate of such a headerencoding approach is K/N.

This embodiment may be referred to as SC header encoding example 6 ashaving an effective rate 1/7, K=64, N=448, (672,504) LDPC code.

As can be seen, two separate and distinct puncturing patterns,punc[1]={63 64 217 218 219 220 221 222}, and punc[2]={225 226 227 228229 230 231 232}, respectively, are applied to the various bits outputfrom the LDPC encoder circuitry (including the header information bitsoutput there from) and the duplicate copy generated there from.

After puncturing, the remaining/non-punctured bits are composed ofc(set1)=c(1:62) U c(65:216) U c(223:232) and c(set2)=c(1:224),respectively.

This embodiment 2500 shows the puncturing being performed therein to usenon-consecutive/non-contiguous puncturing. For example, anon-consecutive/non-contiguous group of bits are punctured. Differentnon-consecutive/non-contiguous portions of the various bits output fromthe LDPC encoder circuitry (including the header information bits outputthere from) and the duplicate copies thereof undergo puncturing.

In this embodiment, certain of the header information bits themselveshave undergo puncturing. Also, in this embodiment as well as in anyembodiment presented herein, any desired means of combination of thebits may be made to generate the final header.

While this embodiment shows an example of combining the bits to generatethe header by employing the first set c(set1) followed by the c(set2),as described above, with respect to any embodiment of the SC PHY headerand OFDM PHY header presented herein, it is again noted that any desiredmeans of combination of the bits may be made to generate the finalheader (e.g., rearranging of the bits in accordance with scrambling,interleaving, etc. including switching the order of any two or morebits; the order in which the header information bits, theremaining/non-punctured bits [whether they be header information bits orparity/redundancy bits] may be emplaced in the final formed header inaccordance with any desired manner or order as a particular embodimentor implementation would prefer or require. For example, while many ofthe embodiments presented herein, the header information bits (which arerepeated) are followed by the parity/redundancy bits (which are alsorepeated). However, the order in which these bits are included to formthe final header may also be changed without departing from the scopeand spirit of the invention (e.g., parity/redundancy bits firstlyfollowed by the header information bits; alternatively: headerinformation bits followed by parity/redundancy bits then followed by acopy/duplicate of the header information bits then followed by acopy/duplicate of the parity/redundancy bits).

FIG. 26 illustrates an embodiment 2600 of performance comparisons ofvarious LDPC codes, each employing a respective header encodingapproach, using SC signaling with QPSK modulation on an AWGNcommunication channel.

The various examples 1, 4, and 5 presented in certain of the previousdiagrams are shown in this diagram to show the relative performancethereof based on a AWGN communication channel.

To compensate for the coding offset incurred by the different effectivecoding rates, the performance curve of example 1 is shiftedappropriately to allow for an accurate comparison.

FIG. 27 illustrates an embodiment 2700 of performance comparisons ofvarious LDPC codes, each employing a respective header encodingapproach, using SC signaling with an exponential decaying PDP Rayleighfading communication channel QPSK modulation.

The various examples 1, 4, and 5 presented in certain of the previousdiagrams are shown in this diagram to show the relative performancethereof based on an exponential decaying PDP Rayleigh fadingcommunication channel QPSK modulation.

Again, as with the previous embodiment 2600, to compensate for thecoding offset incurred by the different effective coding rates, theperformance curve of example 1 is shifted appropriately to allow for anaccurate comparison.

FIG. 28A illustrates an embodiment of a method 2800 for processingheader information bits thereby generating a header.

Referring to method 2800 of FIG. 28A, the method 2800 begins byscrambling header information bits thereby generating scrambled headerinformation bits, as shown in a block 2810. The method 2800 continues bypadding at least one bit (e.g., 0-valued bits) to the scrambled headerinformation bits thereby generating padded bit block, as shown in ablock 2820.

The method 2800 then operates by encoding padded bit block therebygenerating coded bits, as shown in a block 2830. The method 2800continues by shortening coded bits (e.g., removing padded bits) therebygenerating shortened coded bits, as shown in a block 2840. The method2800 then operates by puncturing at least one bit from the shortenedcoded bits thereby generating punctured bits, as shown in a block 2850.

The method 2800 continues by spreading (e.g., combining, repeating,etc.) the punctured bits thereby generating header, as shown in a block2860. The method 2800 then operates by emplacing header within frame, asshown in a block 2870.

FIG. 28B illustrates an embodiment of an alternatively method 2800 forprocessing header information bits thereby generating a header.

Referring to method 2801 of FIG. 28B, the method 2801 begins byduplicating at least one portion of coded bits (or shortened coded bits)(e.g., parity/redundancy bits of LDPC codeword) thereby generatingduplicated bits, as shown in a block 2811. The method 2801 then operatesby puncturing, in accordance with a first puncturing pattern, at leastone bit from the shortened coded bits thereby generating first puncturedbits, as shown in a block 2821.

The method 2801 continues by puncturing, in accordance with a secondpuncturing pattern, at least one bit from the shortened coded bitsthereby generating second punctured bits, as shown in a block 2831. Themethod 2801 then operates by spreading (e.g., combining, repeating,etc.) the first punctured bits and the second punctured bits therebygenerating header, as shown in a block 2841. The method 2800 thenoperates by emplacing header within frame, as shown in a block 2851.

It is noted that the various modules (e.g., encoding modules, decodingmodules, header encoding modules, etc.) described herein may be a singleprocessing device or a plurality of processing devices. Such aprocessing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on operationalinstructions. The operational instructions may be stored in a memory.The memory may be a single memory device or a plurality of memorydevices. Such a memory device may be a read-only memory (ROM), randomaccess memory (RAM), volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, and/or any device that storesdigital information. It is also noted that when the processing moduleimplements one or more of its functions via a state machine, analogcircuitry, digital circuitry, and/or logic circuitry, the memory storingthe corresponding operational instructions is embedded with thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. In such an embodiment, a memorystores, and a processing module coupled thereto executes, operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated and/or described herein.

The present invention has also been described above with the aid ofmethod steps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claimed invention.

The present invention has been described above with the aid offunctional building blocks illustrating the performance of certainsignificant functions. The boundaries of these functional buildingblocks have been arbitrarily defined for convenience of description.Alternate boundaries could be defined as long as the certain significantfunctions are appropriately performed. Similarly, flow diagram blocksmay also have been arbitrarily defined herein to illustrate certainsignificant functionality. To the extent used, the flow diagram blockboundaries and sequence could have been defined otherwise and stillperform the certain significant functionality. Such alternatedefinitions of both functional building blocks and flow diagram blocksand sequences are thus within the scope and spirit of the claimedinvention.

One of average skill in the art will also recognize that the functionalbuilding blocks, and other illustrative blocks, modules and componentsherein, can be implemented as illustrated or by discrete components,application specific integrated circuits, processors executingappropriate software and the like or any combination thereof.

Moreover, although described in detail for purposes of clarity andunderstanding by way of the aforementioned embodiments, the presentinvention is not limited to such embodiments. It will be obvious to oneof average skill in the art that various changes and modifications maybe practiced within the spirit and scope of the invention, as limitedonly by the scope of the appended claims.

1. An apparatus, comprising: a padding circuitry that is operative topad at least one bit to a plurality of header information bits therebygenerating a padded bit block; an LDPC (Low Density Parity Check)encoder circuitry, coupled to the padding circuitry, that is operativeto encode the padded bit block thereby generating a plurality of LDPCcoded bits; a shorten/puncture circuitry, coupled to the encodercircuitry, that is operative to: shorten at least one bit within theplurality of LDPC coded bits that corresponds to the at least one bitpadded to the plurality of header information bits thereby generating aplurality of shortened coded bits; perform repetition coding on theplurality of shortened coded bits thereby generating at least oneduplicate of the plurality of shortened coded bits; puncture at leastone of the plurality of shortened coded bits thereby generating a firstplurality of remaining bits; and puncture at least one of the at leastone duplicate of the plurality of shortened coded bits therebygenerating a second plurality of remaining bits; and a spreadercircuitry, coupled to the shorten/puncture circuitry, that is operativeto process the first plurality of remaining bits and the secondplurality of remaining bits thereby generating a header.
 2. Theapparatus of claim 1, further comprising: a scrambler circuitry that isoperative to scramble the plurality of header information bits beforethe plurality of header information bits is provided to the paddingcircuitry.
 3. The apparatus of claim 1, wherein: the header is emplacedinto a signal that is launched from the apparatus into a communicationchannel using single carrier signaling.
 4. The apparatus of claim 1,wherein the spreader circuitry is operative to generate the header byarranging: the plurality of header information bits; followed by aduplicate of plurality of header information bits; followed by the firstset of remaining bits; and followed by the second set of remaining bits.5. The apparatus of claim 1, wherein the spreader circuitry is operativeto generate the header by arranging: the plurality of header informationbits; followed by the first set of remaining bits; followed by aduplicate of plurality of header information bits; and followed by thesecond set of remaining bits.
 6. The apparatus of claim 1, wherein: theat least one duplicate of the plurality of shortened coded bits includesa first duplicate of the plurality of shortened coded bits and a secondduplicate of the plurality of shortened coded bits; and theshorten/puncture circuitry is operative to: puncture at least one of thefirst duplicate of the plurality of shortened coded bits therebygenerating the second plurality of remaining bits; and puncture at leastone of the second duplicate of the plurality of shortened coded bitsthereby generating a third plurality of remaining bits; and the spreadercircuitry is operative to process the first plurality of remaining bits,the second plurality of remaining bits, and the third plurality ofremaining bits thereby generating the header.
 7. The apparatus of claim6, wherein: the header is emplaced into a signal that is launched fromthe apparatus into a communication channel using orthogonal frequencydivision multiplexing (OFDM) signaling.
 8. The apparatus of claim 6,wherein the spreader circuitry is operative to generate the header byarranging: the plurality of header information bits; followed by a firstduplicate of plurality of header information bits; followed by a secondduplicate of plurality of header information bits; followed by the firstset of remaining bits; followed by the second set of remaining bits; andfollowed by the third set of remaining bits.
 9. The apparatus of claim6, wherein the spreader circuitry is operative to generate the header byarranging: the plurality of header information bits; followed by thefirst set of remaining bits; followed by a first duplicate of pluralityof header information bits; followed by the second set of remainingbits; followed by a second duplicate of plurality of header informationbits; and followed by the third set of remaining bits.
 10. The apparatusof claim 1, wherein: the apparatus is operative to generate a frame thatincludes the header and data; and the header indicates a plurality ofinformation corresponding to the frame or data including frame length, acode type by which the data are encoded, a code rate by which the dataare encoded, and at least one modulation by which symbols of the dataare modulated.
 11. The apparatus of claim 1, wherein: the apparatus is acommunication device; and the communication device is implemented withinat least one of a satellite communication system, a wirelesscommunication system, a wired communication system, and a fiber-opticcommunication system.
 12. An apparatus, comprising: a scramblercircuitry that is operative to scramble a plurality of headerinformation bits thereby generating a scrambled plurality of headerinformation bits; a padding circuitry that is operative to pad at leastone bit to a scrambled plurality of header information bits therebygenerating a padded bit block; an LDPC (Low Density Parity Check)encoder circuitry, coupled to the padding circuitry, that is operativeto encode the padded bit block thereby generating a plurality of LDPCcoded bits; a shorten/puncture circuitry, coupled to the encodercircuitry, that is operative to: shorten at least one bit within theplurality of LDPC coded bits that corresponds to the at least one bitpadded to the scrambled plurality of header information bits therebygenerating a plurality of shortened coded bits; perform repetitioncoding on the plurality of shortened coded bits thereby generating atleast one duplicate of the plurality of shortened coded bits; employ afirst puncturing pattern to puncture at least one of the plurality ofshortened coded bits thereby generating a first plurality of remainingbits; and employ a second puncturing pattern to puncture at least one ofthe at least one duplicate of the plurality of shortened coded bitsthereby generating a second plurality of remaining bits; and a spreadercircuitry, coupled to the shorten/puncture circuitry, that is operativeto process the first plurality of remaining bits and the secondplurality of remaining bits thereby generating a header; and wherein:the apparatus is operative to generate a frame that includes the headerand data; and the header indicates a plurality of informationcorresponding to the frame or data including frame length, a code typeby which the data are encoded, a code rate by which the data areencoded, and at least one modulation by which symbols of the data aremodulated.
 13. The apparatus of claim 12, wherein: the header isemplaced into a signal that is launched from the apparatus into acommunication channel using single carrier signaling.
 14. The apparatusof claim 12, wherein the spreader circuitry is operative to generate theheader by arranging: the scrambled plurality of header information bits;followed by a duplicate of the scrambled plurality of header informationbits; followed by the first set of remaining bits; and followed by thesecond set of remaining bits.
 15. The apparatus of claim 12, wherein thespreader circuitry is operative to generate the header by arranging: thescrambled plurality of header information bits; followed by the firstset of remaining bits; followed by a duplicate of the scrambledplurality of header information bits; and followed by the second set ofremaining bits.
 16. The apparatus of claim 12, wherein: the at least oneduplicate of the plurality of shortened coded bits includes a firstduplicate of the plurality of shortened coded bits and a secondduplicate of the plurality of shortened coded bits; and theshorten/puncture circuitry is operative to: puncture at least one of thefirst duplicate of the plurality of shortened coded bits therebygenerating the second plurality of remaining bits; and puncture at leastone of the second duplicate of the plurality of shortened coded bitsthereby generating a third plurality of remaining bits; and the spreadercircuitry is operative to process the first plurality of remaining bits,the second plurality of remaining bits, and the third plurality ofremaining bits thereby generating the header.
 17. The apparatus of claim16, wherein: the header is emplaced into a signal that is launched fromthe apparatus into a communication channel using orthogonal frequencydivision multiplexing (OFDM) signaling.
 18. The apparatus of claim 16,wherein the spreader circuitry is operative to generate the header byarranging: the scrambled plurality of header information bits; followedby a first duplicate of the scrambled plurality of header informationbits; followed by a second duplicate of the scrambled plurality ofheader information bits; followed by the first set of remaining bits;followed by the second set of remaining bits; and followed by the thirdset of remaining bits.
 19. The apparatus of claim 16, wherein thespreader circuitry is operative to generate the header by arranging: thescrambled plurality of header information bits; followed by the firstset of remaining bits; followed by a first duplicate of the scrambledplurality of header information bits; followed by the second set ofremaining bits; followed by a second duplicate of the scrambledplurality of header information bits; and followed by the third set ofremaining bits.
 20. The apparatus of claim 12, wherein: the apparatus isa communication device; and the communication device is implementedwithin at least one of a satellite communication system, a wirelesscommunication system, a wired communication system, and a fiber-opticcommunication system.
 21. A method, comprising: padding at least one bitto a plurality of header information bits thereby generating a paddedbit block; employing an LDPC (Low Density Parity Check) encodercircuitry to encode the padded bit block thereby generating a pluralityof LDPC coded bits; shortening at least one bit within the plurality ofLDPC coded bits that corresponds to the at least one bit padded to theplurality of header information bits thereby generating a plurality ofshortened coded bits; performing repetition coding on the plurality ofshortened coded bits thereby generating at least one duplicate of theplurality of shortened coded bits; employing a first puncturing patternto puncture at least one of the plurality of shortened coded bitsthereby generating a first plurality of remaining bits; and employing asecond puncturing pattern to puncture at least one of the at least oneduplicate of the plurality of shortened coded bits thereby generating asecond plurality of remaining bits; and processing the first pluralityof remaining bits and the second plurality of remaining bits therebygenerating a header.
 22. The method of claim 21, further comprising:scrambling the plurality of header information bits before padding theat least one bit to the plurality of header information bits.
 23. Themethod of claim 21, further comprising: emplacing into a signal that islaunched into a communication channel using single carrier signaling.24. The method of claim 21, further comprising generating the header byarranging: the plurality of header information bits; followed by aduplicate of plurality of header information bits; followed by the firstset of remaining bits; and followed by the second set of remaining bits.25. The method of claim 21, further comprising generating the header byarranging: the plurality of header information bits; followed by thefirst set of remaining bits; followed by a duplicate of plurality ofheader information bits; and followed by the second set of remainingbits.
 26. The method of claim 21, wherein: the at least one duplicate ofthe plurality of shortened coded bits includes a first duplicate of theplurality of shortened coded bits and a second duplicate of theplurality of shortened coded bits; and the shorten/puncture circuitry isoperative to: puncture at least one of the first duplicate of theplurality of shortened coded bits thereby generating the secondplurality of remaining bits; and puncture at least one of the secondduplicate of the plurality of shortened coded bits thereby generating athird plurality of remaining bits; and the spreader circuitry isoperative to process the first plurality of remaining bits, the secondplurality of remaining bits, and the third plurality of remaining bitsthereby generating the header.
 27. The method of claim 26, furthercomprising: emplacing into a signal that is launched into acommunication channel using orthogonal frequency division multiplexing(OFDM) signaling.
 28. The method of claim 26, further comprisinggenerating the header by arranging: the plurality of header informationbits; followed by a first duplicate of plurality of header informationbits; followed by a second duplicate of plurality of header informationbits; followed by the first set of remaining bits; followed by thesecond set of remaining bits; and followed by the third set of remainingbits.
 29. The method of claim 26, further comprising generating theheader by arranging: the plurality of header information bits; followedby the first set of remaining bits; followed by a first duplicate ofplurality of header information bits; followed by the second set ofremaining bits; followed by a second duplicate of plurality of headerinformation bits; and followed by the third set of remaining bits. 30.The method of claim 21, wherein: the apparatus is operative to generatea frame that includes the header and data; and the header indicates aplurality of information corresponding to the frame or data includingframe length, a code type by which the data are encoded, a code rate bywhich the data are encoded, and at least one modulation by which symbolsof the data are modulated.
 31. The method of claim 21, wherein: themethod is performed within a communication device; and the communicationdevice is implemented within at least one of a satellite communicationsystem, a wireless communication system, a wired communication system,and a fiber-optic communication system.